Liquid crystal display apparatus

Abstract

The present invention provides a liquid crystal display apparatus realizing an improved view angle characteristic of luminance and higher response speed. A sub-pixel group is provided with a plurality of sub-pixels. At the time of display driving on liquid crystal elements of each pixel, space-divisional-driving which allows each of the first and the second sub-pixels to be driven separately is performed. By the space-divisional-driving, fluctuations in the gamma characteristic in the case of seeing a display screen from an oblique direction are effectively dispersed, and the view angle characteristic of luminance improves. Area of the first sub-pixel is set to be smaller than whole area of the sub-pixel group. As a result, the drive voltage to be applied to the first sub-pixel at the time of lower gray level becomes high, and response speed improves.

1. A liquid crystal display apparatus comprising:
 a plurality of pixels arranged in a matrix as a whole and each having a liquid crystal element, each of the pixels including a first sub-pixel and a sub-pixel group having a plurality of second sub-pixels, a lower gray level voltage being applied to the first sub-pixel, and higher gray level voltages with different values being applied to the second sub-pixels, respectively; and 
 driving means for driving the liquid crystal elements in the pixels by applying drive voltage based on a video signal, 
 wherein 
 area of the first sub-pixel is smaller than whole area of the sub-pixel group, 
 the driving means drives each of the pixels based on the video signal in a manner of space-divisional-driving which allows each of the first and the second sub-pixels to be driven separately, 
 the sub-pixel group includes two sub-pixels so that each of the pixels has three respective sub-pixels which include a respective first sub-pixel and respective two second sub-pixels such that the three respective sub-pixels for each pixel are separate or distinct from the sub-pixels of other pixels, and 
 the driving means drives each second sub-pixel of the respective two second sub-pixels with a different drive voltage. 
 
     
     
       2. The liquid crystal display apparatus according to  claim 1 , wherein the driving means:
 applies a first input-versus-output luminance characteristic, in which output luminance rises from a first input luminance position, to the first sub-pixel; 
 applies a second input-versus-output luminance characteristic, in which output luminance rises from a second input luminance position which is higher in position than the first input luminance position, to one of the two second sub-pixels; and 
 applies a third input-versus-output luminance characteristic, in which output luminance rises from a third input luminance position which is higher in position than the second input luminance position, to the other one of the two second sub-pixels, 
 thereby performing the space-divisional-driving which allows each of the first and the two second sub-pixels to be driven separately. 
 
     
     
       3. The liquid crystal display apparatus according to  claim 2 , wherein each of the pixels includes:
 a first switching element for driving the first sub-pixel; a second switching element for driving the sub-pixel group; 
 a capacitive element provided between the second switching element and the other one of the two second sub-pixels, and 
 the driving means performs the space-divisional-driving on the first and the two second sub-pixels through using a first look-up table in which input luminance level of the video signal is associated with output luminance level to be applied to the first sub-pixel and output luminance level to be applied to the sub-pixel group. 
 
     
     
       4. The liquid crystal display apparatus according to  claim 3 , wherein the driving means drives each of the pixels in a line-sequential manner, and
 a single gate line and two data lines are provided in correspondence with each of pixels, the gate line selecting a pixel to be driven in the line-sequential manner, the two data lines supplying the drive voltage to the pixel to be driven. 
 
     
     
       5. The liquid crystal display apparatus according to  claim 3 , wherein the driving means drives each of the pixels in a line-sequential manner, and
 two gate lines and a single data line are provided in correspondence with each of pixels, the two gate lines selecting a pixel to be driven in the line-sequential manner, the single data line supplying the drive voltage to the pixel to be driven. 
 
     
     
       6. The liquid crystal display apparatus according to  claim 2 , wherein each of the pixels includes three switching elements for driving the first and the two second sub-pixels, respectively, and
 the driving means performs the space-divisional-driving on the first and the two second sub-pixels through using a second look-up table in which input luminance level of the video signal is associated with output luminance level to be applied to the first sub-pixel and output luminance level to be applied to each of the two second sub-pixels. 
 
     
     
       7. The liquid crystal display apparatus according to  claim 1 , wherein the area of the first sub-pixel is equal to or less than ⅓ of whole area of the pixel. 
     
     
       8. The liquid crystal display apparatus according to  claim 7 , wherein the following equation (1) is satisfied, where ‘Sa’ is area of the first sub-pixel, ‘Sb 1 ’ is area of one of the two second sub-pixels, and ‘Sb 2 ’ is area of the other one of the two second sub-pixels
   Sa<Sb1<Sb2  (1).
 
 
     
     
       9. The liquid crystal display apparatus according to  claim 1 , wherein the driving means performs the space-divisional-driving while executing overdrive process on the drive voltage of each of the first and the second sub-pixels so that an overdrive level for the first sub-pixel is different from that for the sub-pixel group. 
     
     
       10. The liquid crystal display apparatus according to  claim 1 , wherein the liquid crystal element includes a liquid crystal in a vertical alignment (VA) mode. 
     
     
       11. A liquid crystal display apparatus comprising:
 a plurality of pixels arranged in a matrix as a whole and each having a liquid crystal element, each of the pixels including a first sub-pixel and a sub-pixel group having a plurality of second sub-pixels, a lower gray level voltage being applied to the first sub-pixel, and higher gray level voltages with different values being applied to the second sub-pixels, respectively; and 
 a driving section for driving the liquid crystal elements in the pixels by applying drive voltage based on a video signal, 
 wherein 
 area of the first sub-pixel is smaller than whole area of the sub-pixel group, 
 the driving section drives each of the pixels based on the video signal in a manner of space-divisional-driving which allows each of the first and the second sub-pixels to be driven separately, 
 the sub-pixel group includes two sub-pixels so that each of the pixels has three respective sub-pixels which include a respective first sub-pixel and respective two second sub-pixels such that the three respective sub-pixels for each pixel are separate or distinct from the sub-pixels of other pixels, and 
 the driving section drives each second sub-pixel of the respective two second sub-pixels with a different drive voltage. 
 
     
     
       12. A liquid crystal display apparatus comprising:
 a plurality of pixels arranged in a matrix as a whole and each having a liquid crystal element, each of the pixels including a first sub-pixel and a sub-pixel group having a plurality of second sub-pixels, a lower gray level voltage being applied to the first sub-pixel, and higher gray level voltages with different values being applied to the second sub-pixels, respectively; and 
 a driving section for driving the liquid crystal elements in the pixels by applying drive voltage based on a video signal, 
 wherein 
 area of the first sub-pixel is smaller than whole area of the sub-pixel group, 
 the driving section drives each of the pixels based on the video signal in a manner of space-divisional-driving which allows each of the first and the second sub-pixels to be driven separately, and 
 the sub-pixel group includes three sub-pixels so that each of the pixels has four respective sub-pixels which include a respective first sub-pixel and respective three second sub-pixels such that the four respective sub-pixels for each pixel are separate or distinct from the sub-pixels of other pixels.